Watermakers for small boats
Below about 35 feet the constraint stops being money and starts being space and amps. The good news is that a small crew needs little water, so the smallest systems in the table are genuinely adequate rather than a compromise.
The power reality. A modest house bank and a small array rule out the kilowatt-class systems entirely. This is 12 V territory, and it is where the low-output energy-recovery units shine.
What matters on small boats
Two people need surprisingly little
At 15 litres a head that is 30 litres a day, which even a 20 L/hr system makes in an hour and a half.
Portable may be the whole answer
No through-hulls, no installer, and it lives in a locker. On a boat used in bursts rather than lived on, that is often the right call.
Watch the current, not just the watts
At 12 V a modest draw is a lot of amps. Cable size and connection quality matter more here than on any larger boat.
Weight and stowage
A portable unit still has to be lifted and stowed. Check the weight against who will actually be carrying it.
Shortlist for small boats
Every system in our table that suits small boats, ordered by fits and stows. Run time and energy below are for 30 litres a day.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Scout SW20 LEDIreported | 12V DC | 20 | 200 | 10.0 | on request |
| Portable 12VDC 34L Rainman | 12V DC | 26–37 | 400 | 12.7 | $4,898 |
| Zen 30 Schenker | 12/24V DC | 30 | 110 | 3.7 | $6,300 |
| Ventura 150 Deluxe Spectra | 12/24V DC | 24 | 108 | 4.5 | $6,000 |
| Ventura 150 Connect Spectra | 12/24V DC | 24 | 108 | 4.5 | $7,400 |
| Modular 12VDC 34L Rainman | 12V DC | 26–37 | 400 | 12.7 | $5,053 |
| Ventura 200 Tropical Spectra · spec unconfirmed | 12/24V DC | 31 | — | not published | $8,200 |
Common questions
- What is the smallest boat that can have a watermaker?
- There is no lower limit in practice — portable 12 V units are used on trailer boats and small cruisers. The constraint is whether you can spare the amps and stow the unit, not the length of the hull.
- Can a small yacht run a watermaker on 12V?
- Yes. Several systems in our table run at 12 V, and the energy-recovery ones make a couple's daily water for a few hundred watt-hours. Pay close attention to cable sizing, because current at 12 V is high for any given draw.
- Is a portable watermaker good for a small boat?
- Often the best fit: no installation, no through-hulls, and it stows away between trips. The trade is setup time each use, which discourages the short regular runs membranes prefer.
Guides that go deeper
Not quite your boat?
How the shortlist is built. 30 litres a day is 2 aboard at 15 litres each — a planning figure for this kind of boat, not a measurement of yours. The list is filtered to systems whose power source suits small boats and ordered by fits and stows. Every figure is the manufacturer’s rated output and draw; Wh per litre is one divided by the other. Methodology.